The present utility model relates to medical blood taking instrument, especially to a safety single use blood taking lancet having a puncture depth that is adjustable. The depth of puncturing into the skin of a human being of this blood taking lancet can be adjusted, so as to adapt to different ages and different kinds of skin layer.
Compared with the general single use safety automatic blood taking lancet, the safety single use automatic blood taking lancet with adjusting head has great advantage in the control of the puncture depth. It changes the previous disadvantage that the blood taking puncture depth could not be changed, in that it can change its puncture depth according to different blood taking objects, such as, for example, adult or children, and male or female, etc., thus can achieve better blood taking effect. In practice, doctors and nurses have given positive review of such products. Also, patients who have had their blood taken welcome these products.
In prior art, there are many kinds of blood taking needles with adjustable puncture depth. Several patent applications relating to adjustable puncture depth have been disclosed in Chinese patents. Among these patents, the following three applications are most related:
1. an utility model named “Adjusting head of blood taking puncture depth”, 01244815.X, filed on Jul. 13, 2001.
2. an utility model named “Improved adjusting head of blood taking puncture depth”, 01263172.8, filed on Oct. 9, 2001.
3. an utility model named “improved safety one-off adjustable blood taking needle”, filed on Nov. 29, 2002.
In the above-mentioned three applications, although they disclosed different adjusting structures, the basic theory is using a screw structure to move out the end face of the needle hole in the corresponding position of the axis, thus adjusting the extended length of the needle. Although this structure has beneficial effect in past practice, it has the following disadvantages: 1) when moving, the adjusting head would move back and forth relative to the shell body. Therefore, there is larger error between the actual regulated quantity and the academic regulated quantity, which leads to decreased precision of the adjustment of the puncture depth; 2) the regulated quantity of each kind is hard to reach an identity; 3) the adjusting head and the shell body connected by the screw structure, which is very complex. Thus, it is very hard to guarantee that the move precision and the product quality of every two components are the same; and 4) the arrangement of the screw structure would increase the volume and the length of the blood taking needle.
On the other hand, as a complete automatic blood taking apparatus, the design of the blast-off structure is very important, because this structure not only relates to the problem of safety and convenience. It also relates to the volume, cost and reliability, and other issues of the blood taking needle. As a product to be introduced to the market, attention should be paid not only to the effect of adjusting head and the effect of blast-off structure, but also to the integrate performance and reliability of the combination of the adjusting head and blast-off structure, thus to make the best optimized overall effect.